Method and apparatus for carrying out a heat exchange between a heat carrier medium and a drum reactor

ABSTRACT

The present invention pertains to the indirect heating or cooling of a drum reactor by the exchange of heat from a heat carrier medium. The heat carrier medium is fed to one or more annular distribution chambers fixedly disposed about a stationary outer wall or jacket, thence through openings in the jacket into the annular space between the jacket and the rotatable drum wall, and finally out to one or more annular collection chambers. The distribution and collection chambers are spaced apart from each other and cause the heat carrier medium to flow longitudinally along the drum for more efficient heat exchange. In addition, the various inlet and exit ports of the alternate distribution chambers are radially spaced from each other such that the heat carrier flow is both longitudinal and rotational about the drum reactor.

United States Patent 1191 Wisz Y 1 METHOD AND APPARATUS FOR CARRYING OUT A HEAT EXCHANGE BETWEEN A HEAT CARRIER MEDIUM AND A DRUM REACTOR [75] Inventor: Edward Wisz,Kaiseraugst,

Switzerland I [73] Assignees: Buss AG, Basel,

Eisenbau Wyhlen AG, Wyhlen/ Deutsc hland. Switzerland [22] Filed: Jan. 12, 1972 [21] Appl. No.: 217,133

[30] Foreign Application Priority Data 1111 3,783,936 Jan. 8, 1974 2,956,348 10/1960 v Mueller 165/89 Primary ExaminerCharles Sukalo f er/19:51am chwaab 811 1 1,

[ 5 7 ABSTRACT The present invention pertains to the indirect heating or cooling of a drum reactor by the exchange of heat from a heat carrier medium. The heat carrier medium is fed to one or more annular distribution chambers fixedly disposed about a stationary outer wall or jacket, thence through openings in the jacket into the annular space between the jacket and the rotatable drum wall, and finally out to one or more annular collection chambers. The distribution and collection chambers are spaced apart from each other and cause the heat carrier medium to flow longitudinally along the drum for more efficient heat exchange. In addition, the various inlet and exit ports of the alternate distribution chambers are radially spaced from each other such that the heat carrier flow is both longitudinal and rotational about the drum reactor.

1 i 3 METHOD AND APPARATUS FGR CARRYTNG OUT A HEAT EXCHANGE BETWEEN A HEAT CARRER MEDIUM AND A DRUM REACTOR The present invention refers to a method for carrying out a heat exchange between an heat carrier medium and a indirectly heatable or coolable drum reactor equipped with a coaxially arranged jacket, the heat carrier medium being circulated through heating or cooling means. A further object of this invention is to propose an apparatusfor carrying out this method, such apparatus comprising a sealed jacket coaxially arranged about a drum reactor as well as means for heating or cooling a heat carrier medium.

Such drum reactors are used in a number of various technical processes and they are constructed as furnance, calcinator, dryer or cooling apparatus, making it thereby necessary to feed or to carry off heat. There are a number of well known advantages, in connection with such drum reactors, i.e. simple and inexpensive construction, well predictable and controllable reaction, etc.

In various application examples, such drum reactors can be directly heated by means of hot steam or hot cumbustion gases, or directly cooled by of blowing the same with a suitable cooling medium. However, there are known an increasing number of application examples which require that a reaction'be performed in vacuum or in a protective gas envelope, the reaction chamber having to be sealed against the surrounding air or gas, thus requiring an indirect heating or cooling. It is therefor object of the present invention to propose a method of heating or cooling a drum reactor under these circumstances, i.e., indirect heating or cooling. A further object of the invention is to improve the methods of indirect heating or cooling already known and to avoid the known disadvantages usually occuring in connection with indirect heating or cooling.

Drum reactors have already been proposed which comprise a heating or coolingjacket arranged coaxially to the drum reactor and which are immersed in a tank by one third of their volume, the tank containing a heat carrier fluid. In order to improve heat exchange between the drum reactor and heat'carrier fluid, is has further been proposed to arrange a number of catch baffles on the outer wall of the drum reactor which carry along, during the rotation of the drum reactor, a certain amount of the heat carrier fluid and splash that part of the wall of the drum reactor which is not immersed in the heat carrier fluid. In the case of a heat carrier medium in vapour or gas form, the wall of the drum reactor typically is blown on by directing the medium through annular pipes disposed in parallel.

With these known arrangements, the efficiency of the heat exchange between heat carrier medium and drum reactor has been considered as not sufficient for a number of important applications. The improved arrangements with catch baffles somewhat raised the efficiency, but resulted in the disadvantages of increased costs and higher flow losses.

It is an object of the present invention to avoid these known disadvantages and to propose a method for carrying out a heat exchange between an heat carrier medium and a indirectly heatable or coolable drum reactor equipped with a coaxially arranged jacket, said heat carrier medium being circulated along said drum reactor and through heating or cooling means for heating or cooling said heat carrier medium. The proposed method comprises the steps of leading said heat carrier medium from said heating or cooling means to a first plenum chamber circumferentially arranged around said jacket of said drum reactor, feeding said heat carrier medium tangentially or radially into said first plenum chamber, leading said heat carrier medium from said first plenum chamber into a chamber between said jacket and said drum reactor and conducting said heat carrier medium along at least a part of the length of the outer wall of said drum reactor, carrying off said heat carrier medium from said chamber between said jacket and said drum reactor into a second plenum chamber circumferentially arranged around said jacket and conducting said heat carrier medium off said second plenum chamber in a tangential or radial direction.

A further object of the present invention is to propose an apparatus for carrying out the just described method, said apparatus comprising a drum reactor, a jacket arranged coaxially to said drum reactor and de fining together with the outer wall of said drum reactor a sealed chamber, further comprising means for heating or cooling a heat carrier medium and means for circulating said heat carrier medium, further comprising at least two annular chambers arranged circumferentially around said jacket and spaced apart from each other, each of said annular chambers being equipped with a connection piece radially or tangentially attached to said annular chambers, said annular chambers communicating with said chamber between said jacket and said drum reactor through a number of openings in said jacket, which opening are arranged along its circumference.

The accompanying drawings show a example of execution of the proposed apparatus. In the following, this apparatus will be described in greater detail, simultaneously explaining the proposed method.

In the drawings,

FIG. 1 shows a schematic view of an installation comprising a drurn reactor and means for heating a heat carrier medium FIG. 2 shows a side elevation of an example of execution of the proposed apparatus, partially cut, and

FIG. 3 shows a section along the lines AA of FIG. 2.

The drum reactor 17 according to FIG. 1 and 2 comprises two races llS arranged in the region of both ends of the reactor 17, said races 15 resting on rolls 16 which are rotatably mounted on suitable supporting blocks on the floor. One end of the drum reactor is equipped with a gear rim l2 meshing with a gear wheel 13, which latter is mounted on the driven shaft of a electric motor 13', thus enabling the drum reactor 17 to be rotated. The reactor 17 is enclosed by a two-part jacket ll, 1' which is supported by a number of stands 14. Further, there are provided a number of annular chambers 2 and 3 which are circumferentially arranged around the jacket ll, 1 and which are spaced from each other by equal distance. Each of these annular chambers 2 and 3 have attached thereto a connection piece for the connection of a heat carrier medium tube. In

let of the drum reactor are fixed and sealed against the rotatable drum by sealing washers 9 and 11, in serted between inlet 8 and drum reactor 17 as well as between outlet 10 and drum reactor 17. The jacket 1, 1 bears on its outer wall a heat insulation layer 20, which, however, is only partly shown in the drawings.

According to FIG. 1, there is provided a mixing chamber 5, to which a burner 4 is connected. The burner 4 heats the gases contained in mixing chamber 5, which gases serve as the heat carrier medium for the system. The gases escape from the chamber 5 escape through a pipe 24. The pipe 24 is connected via control members 18, to every second of the annular chambers 3. The remaining annular chambers 2 are connected via second control members 19 to an exhaust pipe 25, which leads to a ventilator 6, which feeds the cooled gases from the annular chambers 2 back to the mixing chamber 5. A part of these cooled gases escape to the atmosphere, after passage through ventilator 6, by means of a throttle or valve 7.

An exemplary process which the described apparatus may perform is as follows: In the mixing chamber 5, the gases are heated up by the burner 4 and enter under pressure the pipe 24. After having passed the control members 18, they enter the annular chambers 3 in radial or tangential direction. In the interior of the charm bers 3, the bases are allowed to expand so that practically all their dynamic flow pressure is transferred to static pressure, with the control members 18 regulated in such a way that there is a higher flow pressure in the pipe 24 which drops to near Zero in the chambers 3. The hot gases with relatively high static pressure and nearly zero flow then pass the slots 21 in the wall of the jacket 1, 1' and enter the chamber between jacket and drum reactor. As can be seen from N6. 2, the gas stream divides, after having passed the slots 21, into two parts, each of which flowing in an opposite direction towards the next slots 22, thereby heating up the wall of the drum reactor 17. In the annular chambers 2 surrounding the slots 22, there is a slight negative pressure generated by the ventilator 6 and controllable by the control members 19. The cooled-down gases pass now through the slots 22 and collect in the annular chambers 2, from where they are drawn off gaining in velocity by the transformation of static pressure to dynamic flow pressure through pipe 25 back into the mixing chamber 5. In order to assure a continuous renewal of the circulating gases, a part of them is blown off through the throttle 7. v

In this way, the flow, the distribution and the drawing-off of the heat carrier medium is vastly improved, whereby a better exploitation of the heat with smaller flow losses due to less flow resistance is achieved. The slight negative pressure in the chamber between jacket 1, 1' and drum reactor 17 allows a simple and efficient construction of the sealing washers 23. A further great advantage is the automatic balance in the distributing system, thus allowing the provision of fewer control valves than normally required. A further problem now solved with the proposed apparatus is the dismantling of the jacket, which may be very easily and rapidly accomplished since the position of the connecting pieces of the annular chambers 2 and 3 are freely selectable by rotation of the chambers.

What I claim is:

1. Heat exchange apparatus for a hollow, cylindrical drum comprising;

a frame;

roller means supporting each end of said drum on said frame for rotation about the axis thereof;

drive means on said frame for imparting rotary motion to said drum;

a cylindrical jacket mounted on said frame and coaxially disposed about the exterior wall of said drum, said jacket defining together with said exterior wall of said drum a sealed, elongated annular cavity;

a plurality of axially spaced annular chambers arranged circumferentially around said cylindrical jacket and fixedly secured therewith;

each of said annular chambers communicating with said cavity through a plurality of openings in said jacket spaced about the entire circumference thereof;

port means radially extending from each of said annular chambers and communicating interiorly thereof;

a heat transfer medium;

means causing the temperature of said heat transfer medium to assume a value different from ambient;

inlet valve means;

outlet valve means;

means feeding said heat transfer medium from said causing means to said inlet valve means;

means exhausting said heat transfer medium from said outlet valve means; and

means connecting alternate ones of said port means of each of said annular chambers to said inlet valve means and said outlet valve means for establishing longitudinal flow of said heat transfer medium about the entire outer cylindrical surface of said drum.

2. The invention as recited in claim 1 wherein said jacket and said annular chambers are constructed in the form of mating semi-cylindrical elements removable exteriorly of said drum.

3. The invention as recited in claim 1 wherein those of said port means connected with said inlet valve means are disposed at a spaced radial position relative to those others of said port means connected with said outlet valve means whereby said established flow of said heat transfer medium is both longitudinal and rotational. 

1. Heat exchange apparatus for a hollow, cylindrical drum comprising; a frame; roller means supporting each end of said drum on said frame for rotation about the axis thereof; drive means on said frame for imparting rotary motion to said drum; a cylindrical jacket mounted on said frame and coaxially disposed about the exterior wall of said drum, said jacket defining together with said exterior wall of said drum a sealed, elongated annular cavity; a plurality of axially spaced annular Chambers arranged circumferentially around said cylindrical jacket and fixedly secured therewith; each of said annular chambers communicating with said cavity through a plurality of openings in said jacket spaced about the entire circumference thereof; port means radially extending from each of said annular chambers and communicating interiorly thereof; a heat transfer medium; means causing the temperature of said heat transfer medium to assume a value different from ambient; inlet valve means; outlet valve means; means feeding said heat transfer medium from said causing means to said inlet valve means; means exhausting said heat transfer medium from said outlet valve means; and means connecting alternate ones of said port means of each of said annular chambers to said inlet valve means and said outlet valve means for establishing longitudinal flow of said heat transfer medium about the entire outer cylindrical surface of said drum.
 2. The invention as recited in claim 1 wherein said jacket and said annular chambers are constructed in the form of mating semi-cylindrical elements removable exteriorly of said drum.
 3. The invention as recited in claim 1 wherein those of said port means connected with said inlet valve means are disposed at a spaced radial position relative to those others of said port means connected with said outlet valve means whereby said established flow of said heat transfer medium is both longitudinal and rotational. 